ST. THOMAS — Following an electrical service interruption which affected all customers in the St. Thomas-St. John district in the wee hours of Saturday morning, WAPA personnel and technical staff from APR Energy have initiated a review of data logs from the three oil-fired generating units to determine the root cause of the units tripping, the authority has said. The units were producing 38 megawatts of electricity when the service interruption occurred at 1:20 a.m. Unit 15 tripped first, Units 26 and 27 fell off-line shortly afterwards, WAPA said.
According to the authority, the unit’s falling off line resulted in a complete loss of generating capacity at the Randolph Harley Power Plant. WAPA’s new Wartsila generators were not on-line at the time of the outage.
Personnel spent several hours working through plant stability challenges before successfully bringing the three APR Energy rental units (25, 26 and 27) on-line which facilitated restoration of service to all customers. Once all electrical feeders were restored, line department personnel responded to reports of isolated service interruptions across St. Thomas, WAPA made known.
“While we believe an electrical fault may have contributed to the initial trip of Unit 15 and that in fact the unit’s protection scheme functioned as it should to protect the generator, we will be taking a closer look to confirm the root cause and work with our partners at APR Energy to understand why their generating units failed to stabilize and take on the additional load when Unit 15 tripped,” said Executive Director Lawrence J. Kupfer.
At mid-afternoon Saturday, the St. Thomas – St. John district was being powered by a combination of Wartsila units and a pair of generators operated by APR Energy.
Kupfer apologized to the community for the inconvenience caused by today’s service interruption and thanked the many men and women of WAPA who responded to the power plant to assist in the recovery of generation, and the subsequent restoration of service to all customers.
All electrical feeders were restored by 9:05 a.m. Saturday.